<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <ul class="nav">
        <li>榴莲</li>
        <li>臭豆腐</li>
        <li>鲱鱼罐头</li>
        <li>大猪蹄子</li>
    </ul>
    <script>
    // 闭包应用-3秒钟之后，打印所有 li 元素的内容
    var lis = document.querySelector('.nav').querySelectorAll('li');
    for (var i = 0; i < lis.length; i++) {
        (function(i) {
            setTimeout(function() {
                console.log(lis[i].innerHTML);
            }, 3000);
        })(i);
    }3
    </script>
</body>
</html>